import java.util.*;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 晓星航
 * Date: 2023-02-22
 * Time: 15:43
 */
class Student {
    private String name;
    private String classes;
    private double score;

    public Student(String name, String classes, double score) {
        this.name = name;
        this.classes = classes;
        this.score = score;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getClasses() {
        return classes;
    }

    public void setClasses(String classes) {
        this.classes = classes;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", classes='" + classes + '\'' +
                ", score=" + score +
                '}';
    }
}
public class TestDemo {
    public static String func1(String str) {
        StringBuilder sb = new StringBuilder();
        int[] array = new int[127];
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if(array[ch] == 0) {
                sb.append(ch);
                array[ch] = 1;
            }
        }
        return sb.toString();
    }
    public static String func2(String str) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if(!sb.toString().contains(ch + "")) {
                sb.append(ch);
            }
        }
        return sb.toString();
    }
    public static String func(String str1,String str2) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < str1.length(); i++) {
            char ch = str1.charAt(i);
            if (!str2.contains(ch+"")){
                sb.append(ch);
            }
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        String str1 = "welcome to bit";
        String str2 = "come";
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < str1.length(); i++) {
            char ch = str1.charAt(i);
            if(!str2.contains(ch+"")) {
                list.add(ch);
            }
        }
        for (char ch:list) {
            System.out.print(ch);
        }
    }
    public static void main4(String[] args) {
        String str1 = "welcome to bit";
        String str2 = "come";
        String ret = func(str1,str2);
        System.out.println(ret);
    }
    public static void main3(String[] args) {
        ArrayList<Integer> integers = new ArrayList<>();
        integers.add(11);
        integers.add(2);
        integers.add(13);
        Collections.sort(integers);
        Collections.reverse(integers);
        System.out.println(integers);
    }
    public static void main2(String[] args) {
        ArrayList<String> list1 = new ArrayList<>();
        List<String> list3 = new ArrayList<>();
        ArrayList<String> list2 = new ArrayList<>(34);

    }
    public static void main1(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNextLine()) {
            String str = scanner.nextLine();
            String ret = func2(str);
            System.out.println(ret);
        }
    }
}
